A heel holder of the above-mentioned type is described for example in DL Pat. No. 61 440. In this known construction, aside from the release spring, a separate torsion spring acts onto a swingable lock, which on the one hand effected the safety release during an overload sliding along a substantially vertical wall and on the other hand facilitates the arbitrary and manual opening of the heel holder operated by a handle. The substantially vertical wall is thereby curved in direction of the sole holder at its end which does not face the upper side of the ski, so that the swivel lock, when the heel pivots due to an overload against the force of the release spring about an axis which lies substantially transversely with respect to the longitudinal axis of the ski, experiences a swivelling against the direction of the swivelling of the entire heel holder, and the swivel lock disengages from a nose, by which it is gripped under in the downhill position, and the heel holder opens. In the case of a manual opening, the handle is operated, and then the heel holder itself first remains in the downhill position and only when the swivel lock has disengaged from the nose (against the force of the torsion spring) can the skier easily step with his ski boot out of the binding. Furthermore, two further springs are provided, through which the ski boot is held clamped in the entire safety ski binding.
A disadvantage of this known construction consists in, even though in particular the main spring is responsible for a safety release, (the torsion spring plays only a subordinate role), the swivel lock, however, being responsible for both the safety release--as a control element--and also for the manual opening--as a releasable locking element. This situation is disadvantageous because the two operations are exposed to entirely different force relationships, and asking one single element to solve both tasks leads automatically to a compromising solution. In this reference, this compromise consists particularly in having to accept large friction forces and furthermore, in the utilization of the two thrust springs, possibly leading to unintended release operations, for example in the case of a bending of the ski.
In a heel holder according to Swiss Pat. No. 505 631, at least one pivotal pawl is provided for locking the spring, which upon reaching a predetermined lifted-off path of the heel holder, is released for disengagement. The pawl is thereby constructed with two arms, and the one end has an abutting surface and serves as a holding hook, and the other end is provided as a stop on a control element for the manual opening, and the control element forms a part of the heel holder. Furthermore, this heel holder has a multimesh linkage, of which one of the member serves as a base frame and one as a hold-down device. The manual opening of this heel holder occurs, according to a product which is manufactured according to this reference, after two steps, namely when first the switch lever is pulled up for example with the ski pole, then the hold-down device has been swung into an intermediate position, then the switch lever is again closed in order to finally enable the heel holder to swing into the highest position, in which the ski boot is released from the clamped position.
Even if in this known construction a certain separation of a release spring and an opening spring (this spring is the spring which biases the switch lever) exists, then this heel holder can again be stepped down only against the force of the main spring both after a manual release and also after a safety release. Since this type of stepping in demands much force, it is disadvantageous, because each type of stepping in can take place only against the force of the release spring. A further disadvantage lies in the above-described opening operation, which, in particular after a difficult fall, can result in additional injuries. Also the utilization of a linkage, which consists of a number of levers, with the joints connected thereto is disadvantageous, in particular the expenditure and wear appearances. However, it must be remarked that this heel holder can be used for both downhill skiing and also for the cross-country skiing.
In a different known construction according to German OS No. 1 728 476, a multimesh linkage is also provided, in which an opening is caused by changing the individual hingedly connected levers with respect to one another, and for the manual opening also in this case the force of the release spring is to be overcome. The aforementioned disadvantageous occur therefore also in the embodiment according to this solution.
The purpose of the invention is now to provide a solution to the above-mentioned disadvantages and to carry out in a heel holder of the above-mentioned type the manual release against the force of a different spring which is independent from the release spring and is substantially weaker with respect to same.
The set purpose is inventively attained by the locking member with the associated release spring and the releasing device for effecting the manual opening with the spring which is associated with it each forming a separate system.
Through the inventive construction, only the force of a practically constant thrust spring must be overcome during a manual opening, which spring force is substantially less than the force of the release spring. The thrust spring has now the purpose to hold the ski boot between the two ski binding parts under a certain initial tension, however, the release spring takes on practically the entire safety function. According to size, the relationship between the two forces is approximately 1:1, 5 to 5, and in addition it must be assured that the force of the release spring increases during a manual release operation, so that the above statements are yet more unfavorable for a manual release against the force of the release spring.
A particularly preferable embodiment of the invention consists in that as a releasing device a release lever, which can be pivoted against the force of at least one thrust spring, is provided and cooperates with at least a pivotal pawl, whereby the pawl in the downhill skiing position of the heel holder holds down the entire housing member above a frame part, which, loaded by a further spring, is released during operation of the release lever and during closing of the binding, after a manual opening, is stepped down by the skier only against the force of the thrust spring.
In this manner it is assured that the heel holder, during a manual opening, must be operated only against the force of the thrust spring and is stepped down by the skier also during closing only against this spring force.
A still further inventive characteristic consists in a spring fork being provided as a base-frame part, the free ends of which fork are remote from the pivot axis therefor, and can each engage a pivotal pawl, which pawls in turn are each spring biased by a thrust spring. In this manner, a structure which is symmetrical with respect to the longitudinal axis of the heel holder is secured, and the lateral arrangement of the structural parts which can be closed together gives the designer a free hand with respect to the inner design of the heel holder.
A still further inventive solution is that the pivotal pawl is loaded by a thrust spring, and the holding hook engages in the closed position of the heel holder a frame part, which forms in turn a spring abutment for the release spring, and that the hold-down device can be pivoted about an axis which extends transversely with respect to the longitudinal axis of the ski, which axis in turn is supported in the base frame. The control element is constructed as a release lever which is pivotal about an axis which extends parallel to the pivot axis and has an operating element, which in the rest position of the release lever rests on the pivotal pawl and in the pivoted position of the release lever holds the pawl against the force of the thrust spring in a position pivoted about the axis, whereby the holding hook disengages from the base frame.